Find out how to apply tile adhesive in a proper way. Our tips and hints for mortar application.
minimum tile coverage with adhesive: 65% for indoor areas, 96% for outdoor and large formats
notched trowels of different sizes depending on a kind of adhesive and tile/slab size
Clean the tile underside and check the tiles
Talcum is often found on the rear side of large format tiles and on resin-bonded slabs. It is absolutely necessary to remove this coating.
Check that the tiles do not present problems of surface absorption. Some kinds of tiles (e.g. polished porcelain tiles) and natural stone have rough, microporous surfaces, making them susceptible to staining and very difficult to clean. In this case preliminary application checks should be performed.
Choose the right trowel
Incorrect use of the notch trowel, wrong size of notches and insufficient tile coverage with adhesive cause poor tile soaking and cavities under tiles. The result is loose or cracked covering. Make sure you have a trowel with large enough notches. The general rule is – the bigger tiles, the bigger notches. For large formats you should use U-shaped or square notched trowel with a notch size 10 mm or 12 mm. Please note that recommended trowel sizes are usually indicated on mortar packages.
One direction draw and mortar coverage
Drag a trowel in one direction with the angle of 60°. Avoid semi-circular moves as this kind of spreading makes voids in the adhesive when slabs are pressed to the substrate. Draw the trowel in one direction. Only such movements guarantee to avoid cavities in the adhesive mortar after pressing the tile against the surface.
For indoor wall covering: at least 65% of the slab should be applied with adhesive mortar. For large formats, floor and outdoor use: 96% of the tile. In case of insufficient coverage, damages in outside covering arise soon as the result of frost.
The combined (butter-floating) method
For large size tiles the mortar should be applied on the substrate and additionally on the tile underside to ensure void-free tile installation. You can apply adhesive on a tile underside with plain or notched edge of a trowel. However if you apply adhesive with different notch sizes for the tile underside and the substrate, it ensures better bond between substrate and tiles.
- This method is particularly recommended for large size tiles.
- Make sure you have a trowel with large enough notches. The general rule is – the bigger tiles, the bigger notches. Please note that recommended trowel sizes are usually indicated on mortar packages.
- Avoid curling movements when spreading adhesive. Draw your trowel in one direction as this way ensures void-free mortar layer under tiles.
Which notch trowel is the right one?
The bigger tiles, the larger notches:
- Tiles up to 30 cm length – notch min. 8 mm
- Tiles up to 60 cm length – notch min. 10 mm
- Tiles above 60 cm length – notch 12 mm
- Large format tiles – notch at least 12 mm.